Convert list to a dictionary with list of values for a duplicate key in Python

Question

I want to convert list to a dictionary that will have duplicate keys so to have all values I would like to have a list of values within a dict.

input as list:

l = ['a', '1', 'b', '2', 'a', '3']

Output should look like this:

d = {'a': ['1','3'], 'b': '2' }

And what defines what a key or a value is? Please be more specific — yatu, Sep 18 '20 at 08:35
https://stackoverflow.com/questions/10664856/make-a-dictionary-with-duplicate-keys-in-python You can refer this — Anushka Raghuvanshi, Sep 18 '20 at 08:40

deadshot · Answer 1 · 2020-09-18T08:48:45.393

0

Try this

res = {}
for i in range(0, len(l), 2):
    res.setdefault(l[i], []).append(l[i+1])
print(res)

Output:

{'a': ['1', '3'], 'b': ['2']}

You can also use zip()

res = {}
for k, v in zip(l[0::2], l[1::2]):
    res.setdefault(k, []).append(v)

edited Sep 18 '20 at 08:48

answered Sep 18 '20 at 08:38

deadshot

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why the step of 2? – Riptide Sep 18 '20 at 08:39
because each pair of elements considered as key and value – deadshot Sep 18 '20 at 08:40
ooh, makes sense – Riptide Sep 18 '20 at 08:41
1

Thanks, @deadshot, you rock, I have been struggling with this but you made it so easy for me. – ripz Sep 18 '20 at 08:53

score 0 · Answer 2 · answered Sep 18 '20 at 08:39

0

from collections import defaultdict

d = defaultdict(list)
l = ['a', '1', 'b', '2', 'a', '3']
for idx,x in enumerate(l):
    if idx % 2 != 0:
        d[l[idx-1]].append(x)
print(d)

output

defaultdict(<class 'list'>, {'a': ['1', '3'], 'b': ['2']})

answered Sep 18 '20 at 08:39

balderman

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Convert list to a dictionary with list of values for a duplicate key in Python

2 Answers2